High velocity foam pump

ABSTRACT

A foam pump including a pump housing with a liquid chamber in fluid communication with a foamable liquid filled container and an air chamber in fluid communication with a high pressure air source through an air inlet. The foam pump also includes a dispensing tube having a wiper seal post with a closed distal end positioned within the pump housing, and an outlet tube with an open distal end positioned outside the pump housing. The wiper seal post includes at least one inlet hole in fluid communication with the liquid chamber, and a check valve near the second open end. The foam pump further includes at least one foam screen in the open end of the outlet tube, a wiper seal slidably positioned around the wiper seal post and in sealing contact with the pump housing and the wiper seal post, and a spring bias to bias the wiper seal in an unactuated position. The wiper seal forms a movable barrier between the liquid chamber and the air chamber and is adapted to slide axially along the wiper seal post past the inlet hole when actuated by high pressure air, thereby allowing the high pressure air to enter the dispenser tube and cause mixing of said air and foamable liquid within the dispensing tube. The mixture is then expelled through the check valve and the foam screen.

TECHNICAL FIELD

The invention herein resides in the art of foam pumps, wherein afoamable liquid and air are combined to dispense a foam product. Moreparticularly, the invention relates to a foam pump wherein airintroduced to the pump at a high velocity acts to actuate the pump andto force an air and foamable liquid mixture through at least one screento produce a uniform high quality foam product.

BACKGROUND OF THE INVENTION

For many years, it has been known to dispense liquids, such as soaps,sanitizers, cleansers, disinfectants, and the like from a dispenserhousing maintaining a refill unit that holds the liquid and provides thepump mechanisms for dispensing the liquid. The pump mechanism employedwith such dispensers has typically been a liquid pump, simply emitting apredetermined quantity of the liquid upon movement of an actuator.Recently, for purposes of effectiveness and economy, it has becomedesirable to dispense the liquids in the form of foam, generated by theinterjection of air into the liquid. Accordingly, the standard liquidpump has given way to a foam generating pump, which necessarily requiresmeans for combining the air and liquid in such a manner as to generatethe desired foam.

Typically foam dispensers generate foam by pumping a foamable liquidstream and an air stream to a mixing area and forcing the mixturethrough a screen to better disperse the air as bubbles within thefoamable liquid and create a more uniform foam product. The more minuteand numerous the air bubbles the thicker and softer the foam, althoughtoo much air can cause the foam to be too dry feeling. The key to adesirable foam product is violent mixing of the foamable liquid and airto disperse the air bubbles within the liquid.

SUMMARY OF THE INVENTION

A foam pump having a pump housing having a liquid chamber and an airchamber, the liquid chamber being in fluid communication with a foamableliquid filled container, and the air chamber being in fluidcommunication with a high pressure air source through an air inlet. Thefoam pump also includes a dispensing tube partially disposed within thepump housing having a wiper seal post with a closed distal endpositioned within the pump housing, and an outlet tube with an opendistal end positioned outside the pump housing. The wiper seal postincludes at least one inlet hole in fluid communication with the liquidchamber, and a check valve near the second open end. Additionally, thefoam pump includes at least one foam screen located in the open end ofthe outlet tube; a wiper seal slidably and coaxially positioned aroundthe wiper seal post, the wiper seal being in sealing contact with aninner wall of the pump housing and with the wiper seal post; and aspring bias positioned within the pump housing to bias the wiper seal inan unactuated position. The wiper seal forms a movable barrier betweenthe liquid chamber and the air chamber and is adapted to slide axiallyalong the wiper seal post away from the outlet tube and past the atleast one inlet hole when actuated by high pressure air. Movement of thewiper seal allows high pressure air to enter the dispenser tube causingmixing of the air and foamable liquid within the dispensing tube, andalso causing expulsion of the mixture through the check valve and the atleast one foam screen.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the foam pump and container according tothe present invention.

FIG. 2 is a cross sectional side view of the foam pump of the presentinvention in an unactuated state.

FIG. 3 is cross sectional side view of the foam pump of the presentinvention in an actuated state.

DETAILED DESCRIPTION OF THE INVENTION

The high velocity foam pump of the present invention is shown in FIGS.1-3 and is generally indicated by the number 10. Foam pump 10 may bepositioned within an opening 12 of a container 14, such as, for example,a refill pouch as shown in FIG. 1. Container 14 has a foamable liquid Stherein, and the portion of foam pump 10 located within container 14 isimmersed in foamable liquid S. Container 14 may in the form of aflexible bag or collapsible bottle, as is known in the art.

Foam pump 10 includes a housing 20, the housing 20 having a liquidchamber 22 and an air chamber 24 therein. Housing 20 is equipped with acap 28 positioned on an open first end 30 of housing 20. Cap 28 has atop planar surface 31 with a hole 32 therein, an outer lip 34 positionedaround the periphery of first end 30 acting to secure cap 28 in place,and a flange 36 extending from top planar surface 31 and into liquidchamber 22. Hole 32 in cap 28 allows for fluid communication betweenliquid chamber 22 and container 14 so that foamable liquid S may flowinto liquid chamber 22 under the effects of gravity or the effects of avacuum created in liquid chamber 22. Housing 20 also includes an airinlet hole 40 in a portion of housing 20 defining air chamber 24. Airinlet hole also includes a seal 42, and is connected to a high pressureair source 43, such as a foot pump, bellows pump, or compressed airpump, for example, thereby allowing for fluid communication between airchamber 24 and the high pressure air source 43. Any conventional methodof generating high pressure air due to a user actuation that is known topersons skilled in the art may be employed. Seal 42 minimizes pressureloss between the high pressure air source and air chamber 24 therebyincreasing the efficiency of foam pump 10.

Housing 20 further includes a bore 46 in which is disposed a dispensingtube 50. Dispensing tube 50 extends through bore 46 to define a wiperseal post 52 as that portion of dispensing tube 50 within housing 20,and defines an outlet tube 54 as that portion extending through bore 46and outside housing 20. Spaced flanges 56 extending radially fromdispensing tube 50 secure dispensing tube 50 in place at bore 46. Moreparticularly, flanges 56 rest on bottom wall 57 of housing 20 to preventdispensing tube 50 from sliding out of housing 20. Flanges 56 may bereplaced by a single flange completely surrounding the periphery ofdispensing tube 50 and functioning in an identical manner to spacedflanges 56. Wiper seal post 52 located within housing 20 has a closeddistal end and is equipped with at least one inlet hole 60 to allowfoamable liquid S to flow from liquid chamber 22 into dispensing tube50, although two or more inlet holes 60 are preferable. Outlet tube 54of dispensing tube 50 has a check valve 62 disposed therein to controlthe outlet flow, check valve 62 being opened by increased pressure in adirection away from inlet hole 60 and returning to a closed state upon adecrease in pressure. Outlet tube 54 also includes at least one foamscreen disposed therein adjacent to an outlet 66 at the distal end ofdispensing tube 50. As seen in the figures, the at least one foam screenmay be in the form of a mixing cartridge 64 which consists of a hollowtube 67 bounded on both ends by mesh screens 68 and 69.

Foam pump 10 further includes a wiper seal 70 slidably positionedcoaxially around wiper seal post 52 within housing 20. Wiper seal 70 isin sealing contact with an internal wall 72 of sidewall 74 of housing 20and with wiper seal post 52, thereby separating liquid chamber 22 fromair chamber 24. More particularly, liquid chamber 22 is defined as thevolume above wiper seal 70 and within sidewall 74 of housing 20.Although liquid chamber 22 is in open communication with container 14through hole 32 in cap 28, for purposes of defining the foam pump 10,the liquid chamber should be viewed as only the volume within housing 20surrounded by sidewall 74. Air chamber 24 is defined as the internalvolume enclosed by wiper seal 70, sidewall 74 and bottom wall 57 ofhousing 20, and around wiper seal post 52. Wiper seal 70 can slidewithin housing 20 and thus, the volumes of liquid chamber 22 andcontainer 14, and air chamber 24, are directly dependent upon theposition of wiper seal 70. An increase in volume of air chamber 24 dueto movement of wiper seal 70 towards cap 28 results in a decrease in thecombined volume of liquid chamber 22 and container 14, and vice versa.Wiper seal 70 is biased to an unactuated position, as seen in FIG. 2, bya biasing spring 80 located between cap 28 and wiper seal 70. Spring 80is held in place near open end 30 of housing 20 by flange 36.

In operation, foam pump 10 is actuated by an input of high pressure airgenerated by a user from high pressure air source 43 through air inlethole 40. The increased pressure in air chamber 24 due to the highpressure air introduced begins actuation of the pump 10 and slides wiperseal 70 towards cap 28 against the biasing forces of spring 80. Whenwiper seal 70 slides completely past the at least one inlet hole 60, thehigh pressure air then enters dispensing tube 50 through the now exposedat least one inlet hole 60 and mixes with foamable liquid S alreadylocated in dispensing tube 50. The pressure established by introducingair from high pressure air source 43 forces check valve 62 to an openposition, allowing the mixture to flow through dispensing tube 50towards outlet 66. Prior to exiting dispensing tube 50 through outlet66, the air and foamable liquid S mixture is forced through at least onefoam screen 64. As a result of this process a high quality foam isdispensed from outlet 66. The high pressure mixing within dispensingtube 50 as well as the passage of the mixture through at least one foamscreen 64 creates a uniformly mixed foam product.

Upon removal of the high pressure air, check valve 62 will return to aclosed position, once again preventing flow of foamable liquid S outthrough dispensing tube 50. The decrease in pressure will also causewiper seal 70 to return to an unactuated position by virtue of thebiasing forces of spring 80. As wiper seal 70 moves axially alongdispensing tube 50 towards air inlet 40 and passes the at least oneinlet hole 60, foamable liquid will flow back into dispensing tube 50due to gravity as well as slight vacuum forces generated by theexpanding volume within liquid chamber 22 and container 14. Thus, uponreturning to an unactuated state, foam pump 10 will be readied forsubsequent actuations.

High pressure air source 43 may be activated by a sensor or by otherwisetouch-less activation as is known in the art, or may include anyconventional manual activation mechanism. High pressure air source 43provides a metered volume of air to air chamber 24 sufficient to forcewiper seal 70 up towards cap 28 and to mix with and force foamableliquid S within dispensing tube 50 out through outlet 66. The volume ofair should not exceed that necessary to actuate foam pump 10 anddispense the foamed liquid S within dispensing tube 50 becausesubsequent to all of foamed liquid S exiting through outlet 66, only airwill be flowing from foam pump 10. However, the metered volume of airshould be sufficient to expel all of the air and foamable liquid mixtureso as to prevent dripping from outlet 66 of residual liquid. Thus, highpressure air source 43 preferably provides a measured amount of highvelocity air specific to the size and volume of air chamber 24 anddispensing tube 50 sufficient to expel the foam, but no more.

In light of the foregoing, it should be apparent that the presentinvention improves the art by providing a foam pump actuated by highvelocity air. While a particular embodiment of this invention has beenthe focus for purposes of disclosing the invention, it should beappreciated that this invention can be modified in various ways withoutdeparting from the general concepts taught herein. Thus, this inventionis not to be limited to or by any particular embodiment; rather, theclaims will serve to define the invention.

1. A foam pump comprising: (a) a pump housing having a liquid chamberand an air chamber, said liquid chamber being in fluid communicationwith a foamable liquid filled container, and said air chamber being influid communication with a high pressure air source through an airinlet; (b) a dispensing tube partially disposed within said pump housinghaving a wiper seal post with a closed distal end positioned within saidpump housing, and an outlet tube with an open distal end positionedoutside said pump housing, said wiper seal post including at least oneinlet hole in fluid communication with said liquid chamber, and a checkvalve near said second open end; (c) at least one foam screen located insaid open end of said outlet tube; (d) a wiper seal slidably andcoaxially positioned around said wiper seal post, said wiper seal beingin sealing contact with an inner wall of said pump housing and with saidwiper seal post; and (e) a spring bias positioned within said pumphousing to bias said wiper seal in an unactuated position; wherein saidwiper seal forms a movable barrier between said liquid chamber and saidair chamber and wherein said wiper seal is adapted to slide axiallyalong said wiper seal post away from said outlet tube and past said atleast one inlet hole when actuated by high pressure air, therebyallowing said high pressure air to enter said dispenser tube and causemixing of said air and foamable liquid within said dispensing tube andcausing expulsion of said mixture through said check valve and said atleast one foam screen.
 2. The foam pump of claim 1, further comprising acap secured to said housing around the periphery of a distal end of saidhousing and adjacent said liquid chamber, said cap having a holetherein.
 3. The foam pump of claim 1, wherein said high pressure airsource provides a metered volume of high pressure air sufficient toactuate the foam pump and expel said air and foamable liquid mixturethrough said outlet tube.